Hot workable copper alloys



Dec. 7, 1937. E. L MUNSON 2,101,626'

HOT WORKABLE COPPER ALLOYS Filed July 13, 1957 c oPPg R NICKEL- ALUMINUM ZINC ALLOYS Maximum and Minimum Copper C onl-enf'for Alloys Con+aining 0.5 +0 3% Aluminum wirh Nickel as lndicai'ed and Remainder Zinc Plus Impurilies.

\NVENTOR ATTORNEYS Patented Dec. 7, 1937 UNITED STATES PATENT, OFFlCE nor WORKABLE c'orrua ALLOYS I Elmer L. Munson, Naugatuck, Conn, assignor to The American Brass Company, Waterbury, Conn.,'a corporation of Connecticut Application July 13, 1937, Serial No. 153,332

8 Claims.

This invention relates to an improvement in non-ferrous alloys and particularly to an alloy whose principal constituent is copper plus various amounts of nickel and zinc, accompanied in the present invention by small but essential amounts .of aluminum, whereby increased strength, resistance to corrosive attack, improved workability and other valuable characteristics are secured. This application is a continuation in part of my prior application Serial No. 750,019, filed October Alloys have been made heretofore consisting essentially of copper, nickel and zinc, commonly called nickel silver, German silver etc., and

are in general use because of their valuable properties. v

This application is directed to the improvement of commercial alloys containing 22% to 53% zinc, 3% to 17% nickel, 40% to 65% copper; and in which the copper is decreased in the range 65% to 52% as the nickel is incrgasedirom the range 3% to 13% to the range 7% to 17% nickel; (in other words if we decrease the copper from 65% to 52% the minimum nickel must be increased from 3% at 65% copper up to 7% at 52% copper,

and the maximum nickel content increases from 13% at 65% copper to 17% at 52% copper) and with from 52% to 40% copper the nickel content is limited tothe range 7% to 12%.

about 58% to about 65% copper, about 3% to 15% nickel and remainder zinc plus impurities are single phase type (alpha solid solution) when heated to temperatures ranging from about 600 C. to about 900 C.- and quenched. Other commercial alloys 'in the aforementioned range namely those containing from about 52% to about 58% copper, about 5% to' 17% nickel have a duplex structure composed of alpha and beta particles.

40 The remainder of the commercial alloys mentioned herein contain from about 40% to about 52% copper, about 7% to about 12% nickel and balance zinc plus impurities and are composed al- 4 most entirely of beta phase particles at all temperatures. l

I have discovered that when-small amounts of "aluminum (from about 0.5% .to about 3%) are addedto the aforementioned nickel silver alloys, new and valuable characteristics are, ob-

tained not heretofore found in said alloys. This addition ofaluminum in amounts from 0.5% to 3% to the copper-nickel-zinc alloys above noted containing about 58% to 65% copper, 3% to 15% nickel, and remainder zinc plus impurities, efiects a change from the single phase alpha solid solu tion, formerly noted in these alloys, to a duplex structure containing alpha plus beta when heated in the annealing temperature range between 00 about 600 C. to approximately 900 C. This is Some of these alloys, namely those with from phase type alloys are not so easily hot worked, if at all. The addition of small amounts of aluminum within the range noted renders that portion of the alpha range extending from about 58% to about 65% copper, from about 3% to about 15% nickel and remainder zinc plus impurities, suitable for hot working such as forging,"rolling and extruding at temperatures ranging from about 650 C. to 900 0.

These new alloys, which from other considerations appear logical commercial ones, can be readily hot rolled, hot pressed, forged and extruded, indicating that they can be economically produced, Many of these alloys (those containing from 52% to 65% copper) can also be cold worked sufiiciently to provide a smooth surface and some measure of work hardening or temper. The accompanying drawing which forms a part of this specification shows the range of alloys involved in the invention of this application. This graph is divided into threeparts-or zones that are thus described.

The area bounded by lines ABEF indicates the best hot and cold working range. It has been found that alloys within these composition limits may be readily and easily hot worked and/or can be reduced by cold working up to about 50%. The composition limits of these alloys are Percent Copper 52 -65 Nick 3 -l2 Alumin a 0.5- 3 Zinc 24 -40.5

and in which the nickel is increased from the range 3% to 8% at 65% copper to the range 7% to 12% at 52% copper 'as the copper is decreased from 65% to 52%. the copper from 65% .to 52% the minimum nickel must be increased from 3% at 65% copper to 7% at 52% copper and the maximum nickel increased from 8% at 65% copper to 12% at 52% copper.)

The area bounded bythe lines BCDE indicates the second range wherein the alloys may be satlsfactorily hot and cold worked. Working of these alloys and especially those alloys richer (In other Words if we decrease.

in nickel and/or aluminum, is not so readily or easily accomplished as with the alloys in the first zone. However, the alloys in this second zone are suitable for some commercial purposes.

The limits for this second zone are:

Percent Copper 52 Nickel 8 -17 Aluminum .5- 3 Zinc 19- -35.5

and in which the nickel is increased from the range 8% to 13% at 65% copper to the range 12% to 17% at 52% copper as the copper is decreased from 65% to 52%. (In other words if we decrease the copper from 65% to 52% the minimum nickel must be increased from 8% at 65% copper to 12% at 52% copper, and the maximum nickel increased from 13% at 65% copper to 17% at 52% copper.)

The area bounded by the lines EHGF indicates the third range or extrusion zone wherein the alloys may be readily and easily extruded, forged, pressed or rolled at a red heat but cannot be cold worked to any commercial extent.

The limits for the third zone are:

Percent Copper 40 -52 Nickel 7 -12 Aluminum 0.5- 3 Zinc 33 -52.5

Percent Copper 40 -65 Nickel 3 -17 Aluminum 0.5- 3 Zinc (plus impurities) 19 --52.5 (remainder) and in which the copper is decreased in the range 65% to 52% as the nickel is increased from the range 3% to 13% to the range 7% to 17% nickel, (in other words if we decrease the copper from 65% to 52% the minimum nickel must be increased from 3% at 65% copper up to 7% at 52% copper, and the maximum nickel content increases from 13% at 65% copper to 17% at 52% copper), and with from 52% to 40% copper the nickel content is limited to the range 7% to 12%.

As an example of intermediate alloys we can take those indicated by dotted line say which shows the minimum nickel at 58% copper is about 5.25% and the maximum nickel is about 15.25%.

Some of thesenew alloys may be hardened to a limited extent by a low temperature heat treatment after heating to 750 C. to 900 C. and quenching with or without a limited amount of cold working as hereinafter noted, and especially those alloys that are least removed from the alpha boundary (at about 65% copper). On the other hand the alloys containing a larger amount of aluminum and also those with less than about 52% copper do not respond appreciably to hardening by low temperature heat sample was 93. nealed at approximately 775 C. for two hours treatment. Likewise no appreciable increase in hardness is obtained after low temperature heat treatment with these alloys when the metal has been reduced about 50% by cold working. That is to say those alloys in the zones ABEF and BCDE can be hardened to a limited extent by low temperature heat treatment.

The maximum hardening temperature for the several annealed alloys, in general, gradually increases as the nickel and/or aluminum is increased from about'400 C. to about 600 C.

The minimum age hardening eifect for any of these alloys is obtained when the aluminum content approaches the maximum at 3% and/or when the material has been reduced as much as 50% by cold working. An example, which shows the efiect ,of cold working on the heat hardenability of these alloys is'now given. An alloy composed of about 63% copper, 5% nickel, 1% aluminum and 31% zinc that had been reduced about 50% by cold rolling showed a Rockwell B hardness of (B scale= ball, 100 kg. load). After being heat treated in an electric muffle furnace at approximately 500 C. the hardness value of this same sample was found to be 101. When the said alloy was annealed at approximately 775 C. quenched the hardness value was 63, which after the specimen was heat treated for two hours at 500 C. was raised to 380.

Another example whichshows the effect of for two hours and increased amounts of aluminum in preventing age hardening is now given. An alloy composed of about 63% copper, 5% nickel, 3% aluminum and 29% zinc that had been reduced about 50% by cold rolling showed a Rockwell B hardness value of 99. After being heat treated in an electric mufiie furnace for two hours at approximately 500 C. the hardness value of this same When the said alloy was anand quenched the B hardness value was 81, which after the specimen was heat treated for two hours at about 500 C., was still '81, indicating little or no increase in hardness when heated at a low temperature.

A further advantage of some of the alloys made in accordance with the present invention is the increase in tensile strength which is obtained by heat treatment at low temperatures. This increase in strength is also accompanied by an increase in elongation. All of the previously mentioned commercial copper-nickel-zinc alloys (paragraph 3, page 1) are not capable of being successfully strengthened or hardened by heat treatment at low temperatures.

Articles may be fabricated from the annealed or wrought alloy, and when finished may be hardened to a limited extent by low temperature heat treatment. The resistance of these new alloys to corrosive attack is superior to that of the previously mentioned ternary commercial alloys.

There are other advantages secured by the addition of aluminum to these alloys. Thus for example loss of zinc during casting is reduced by the protective film produced by the aluminum on the metal. Also, the color efiect is maintained by the aluminum addition so that it is possible to reduce the nickel about one or two percent without loss of proper color, and thus reduce the cost of the alloy.

With the aluminum addition pickling is more or less unnecessary for heavy gauges, and there is no heavy scale with thin gauge metal.

In short these new alloys are suitable for the operations and uses peculiar to the brass and copper industries. I

To total one hundred percent the remainder in the range above noted is more advantageously zinc, but in practice elements other than zinc may be present in slight amounts without injury to the resultant product. Thus, for example, it is common practice to add a small amount of manganese to copper-nickel-zinc alloys and this metal (up to 0.5%) may be added to my alloy. Because it cannot be avoided Without too much expense in refining the constituent metals, there may be and usually are some lead and iron present.

In view of the fact that my improvement applies to a great number of copper-nickel-zincaluminum alloys, it is impossible to state all of the commercially useful alloys in the group.

However, for informative purposes I am listing a few of the most important alloys which because of my invention are a great improvement over the mentioned copper-nickel-zinc alloys.

52% copper that have been work hardened by drawing or rolling can be softened somewhat by annealing at about 800 C. and quenching in cold water, and, if desired, can again be hardened by cold working. The annealed or work hardened metal, whether in' the form of sheet, rod, tube, etc. can be readily fabricated into the finished product and then hardened somewhat by heat treatment at a low temperature. This hardening by low temperature heat treatment afterfabrication is suitable for such articles as nuts, bolts, nipples, valves, keys, clock parts, and the like.

They have also been found to-be corrosion resistant and characterized by the presence of a protective surface film, and some of the alloys can be hardened by heat treatment at low temperatures (approximately 300 C. to 600 C. for periods of about two hours or less), but they can'also be hardened by heat treating for longer periods of time at lower temperatures (150 C. to 300 C.)

These new alloys containing aluminum are particularly satisfactory for certain uses when not hardened by low temperature heat treatment as their resistance to corrosive attack isconsiderably better than that of the alloys without the aluminum. They also have good strength and elongation and can be fabricated into various articles.

These alloys are also useful for welding and for welding rods, and may be brazed. In addi-' tion to their workability and adaptability to-be forged, pressed and extruded some of the alloys, namely those containing more than 52% copper, may be drawn into rods, wire, tubes, sheets and shapes, and other metal articles.

Having thus set forth the nature of my invention, what I-claim is:

8 1. An alloy composed of copper, nickel, zinc and aluminum in proportions within the following ranges,

, Percent Copper 40 to 65 -Nickel 3 to 17 Aluminum 0.5 to 3 Zinc (plus impurities) 19 to 52.5

and in which as the copper is decreased from 65% to 52% the minimum nickel is increased from 3% at 65% copper up to 7% at 52% copper and the maximum nickel content increases from 13% at 65% copper to 17% at 52% copper; and with from 52% to 40% copper the nickel content is limited to the range 7% to 12%.

2. An alloy characterized by being workable hot and cold composed of copper, nickel, zinc and aluminum in proportions within the following ranges,

Percent Copper 52 to 65 Nickel 3 to 12 Aluminum 1 0.5 to 3 Zinc (plus impurities) 24 to 40.5

and in which the nickel is increased from the range 3% to 8% at 65% copper to the range 7% to 12% at 52% copper as the copper is decreased from 65% to 52%.

3. An alloy characterized by being workable hot and cold composed of copper, nickel, zinc and aluminum in proportions within the following ranges,

Percent Copper 52 to 65 Nickel 3 to 17 Aluminum"; 0.5 to 3 Zinc (plus impurities) 19 to 40.5

and in which the nickel is increased from the range 3% to 13% at, 65% copper to the range 7% to 17% at 52% copper as the copper is decreased from 65% to 52%.

'4. An alloy characterized by being hot workable composed of copper, nickel, aluminum and zinc in proportions within the following ranges,

. Percent Copper 40 to 52 Nickel 7 to 12 Aluminum -4. 0.5 to 3 Zinc (plus impurities) 33 'to 52.5

5. An alloy composed of approximately 63% 2 copper, 10% nickel, 1% aluminum, and-zinc re-- mainder. 7

8. A heat hardened and strengthened copper alloycomposed of copper, nickel, aluminum and zinc in proportions within the following ranges,

, Percent Copper. 52 to 65 Nickel 3 to 1'7 A1uminum 0.5 to 3 Zinc (plus impurities) 19 to 40.5

and in which the nickel isincreased from the range,3% to 13% at 65% copper to the range 7% to 17% at 52% copper as the copper is' decreased from 65% to 52%.

ELMER L. MUNSON. 

